1. Field
Example embodiments relate to a memory device and a method of fabricating the same. More particularly, example embodiments relate to a memory device having an improved reliability and a method of fabricating the same.
2. Description of the Prior Art
A memory device has been diversely applied to an apparatus, such as a microcontroller, a credit card, and the like. As one of such memory device, a flash memory device has been developed.
For example, a flash memory device may include a charge trap type flash memory device or a floating gate type flash memory device. The charge trap type flash memory device may have a structure in which a tunneling dielectric layer, a charge trap layer, a blocking dielectric layer, and an upper electrode are sequentially formed on a semiconductor substrate. The floating gate type flash memory device may have a structure in which a tunneling dielectric layer, a floating gate, a blocking dielectric layer, and an upper electrode are sequentially formed on a semiconductor substrate. The charge trap layer (or the floating gate) is designed so that an operating voltage is applied from the upper electrode to the charge trap layer (or the floating gate) to produce an electric potential difference between the charge trap layer (or the floating gate) and the semiconductor substrate. Therefore, electrons are injected from the semiconductor substrate to the charge trap layer (or the floating gate) or electrons are emitted from the charge trap layer (or the floating gate) to the substrate.
Recently, with the integration of devices, dimensions of memory cells and peripheral circuits have been miniaturized, and due to such a tendency and energy efficiency, the operating voltage of a memory device has been lowered. In a flash memory device, charge inflow and maintenance is very important in controlling memory device signals and securing the reliability. Further, the properties and characteristics of dielectric layers, e.g., a tunneling dielectric layer and a blocking dielectric layer, play an important role in securing the reliability of a flash memory device.